In Marxist circles it is common to refer to Karl Marx’s The Civil War in France for a theoretical analysis of the historical significance of the Paris Commune, and to Prosper-Olivier Lissagaray’s History of the Commune of 1871 for a description of the facts surrounding the insurrection of the Paris workers and its repression by the National Assembly led by Adolphe Thiers. What is less well-known is that Marx himself oversaw the German translation of Lissagaray’s book and made numerous additions (...) to it. In this article we describe Marx’s addenda to Lissagaray’s work, showing how they contribute to concretising his analysis of the Paris Commune and how they relate to the split in the International Working Men’s Association between Marxists and anarchists that took place after the Commune’s defeat. We also show how Marx’s additions to the German version of Lissagaray’s book were linked to his involvement with the recently created Socialist Workers’ Party of Germany and to his criticism of the programme it had adopted at the congress celebrated in the city of Gotha. (shrink)